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608 lines
28 KiB
608 lines
28 KiB
PAGE 60,150
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;***************************************************************************
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;* MEMORY.ASM
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;*
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;* Routines used to handle the read/write random memory API
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;*
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;***************************************************************************
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INCLUDE TOOLPRIV.INC
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INCLUDE WINDOWS.INC
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;** Symbols
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SI_CRITICAL EQU 1
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DI_CRITICAL EQU 2
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;** Imports
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externA __AHINCR
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externFP GlobalEntryHandle
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externNP HelperHandleToSel
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sBegin CODE
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assumes CS,CODE
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assumes DS,DATA
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; MemoryRead
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; Uses the passed in selector and offset to read memory into a user-
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; specified buffer. This works for >64K segments and, if code, may
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; have been discarded.
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;
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; This function is normally used for heap selectors. However, if
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; a non-global heap selector is used, it must be less than 64K on
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; a 286.
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;
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; Prototype:
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; DWORD MemoryRead(
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; WORD wSel, /* Selector to read from */
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; DWORD dwOffset, /* Offset to read at */
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; LPSTR lpBuffer, /* Buffer to put data into */
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; DWORD dwcb) /* Number of characters to read */
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; Returns number of characters read (ends at segment limit)
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cProc MemoryRead, <FAR,PUBLIC>, <si,di,ds>
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parmW wSelector
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parmD dwOffset
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parmD lpBuffer
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parmD dwcb
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localD dwcbCopied
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localV Global,<SIZE GLOBALENTRY>
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cBegin
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;** Make sure the segment is present. We only will fault the
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;** segment in if it is a code segment
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cCall HelperHandleToSel, <wSelector> ;Convert to sel from handle
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mov wSelector, ax ;Save it so we have a good sel
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mov cx, ax
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push WORD PTR lpBuffer[2] ;Convert handle to selector
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cCall HelperHandleToSel
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mov WORD PTR lpBuffer[2], ax ;Save converted handle
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lar ax,cx ;Get the access rights
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jnz MR_ShortBad ;Failed. It's bad
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test ax,8000h ;Is it present?
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jnz MR_Present ;Yes
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test ax,0800h ;This bit set for code segments
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jnz MR_FaultIn ;Code segment, fault it in
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MR_ShortBad:
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jmp MR_Bad ;Return error
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MR_FaultIn:
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mov es,wSelector ;Get the selector in ES.
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mov al,es:[0] ;Must be at least one byte long
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MR_Present:
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;** Check this block's length. We use the global heap functions
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;* to do this because they check in the arena for the length.
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;* This is the only way to get lengths of 286 heap blocks
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;** beyond 64K.
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mov ax,SIZE GLOBALENTRY ;Get the size of the structure
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mov WORD PTR Global.ge_dwSize[0],ax ;Save in the structure
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mov WORD PTR Global.ge_dwSize[2],0 ;Clear the HIWORD
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lea ax,Global ;Point to the structure
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cCall GlobalEntryHandle, <ss,ax,wSelector>
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or ax,ax ;Was this a valid selector?
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jnz MR_HeapSel ;Yes, this is a heap selector
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;** If this wasn't a heap selector, we get the length with an LSL.
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;** When used like this, 64K is the max on a 286
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MR_NonHeap:
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mov bx,wSelector ;Get the selector
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mov ax,__WinFlags ;Get the flags
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test ax,WF_CPU286 ;286?
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jz MR_32BitSize ;No, do 32 bit size stuff
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lsl dx,bx ;Get length in DX
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mov WORD PTR Global.ge_dwBlockSize[0],dx ;Put in GLOBALENTRY struct
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mov WORD PTR Global.ge_dwBlockSize[2],0
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jmp SHORT MR_HeapSel
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MR_32BitSize:
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.386p
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lsl edx,ebx
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mov Global.ge_dwBlockSize,edx ;Put in GLOBALENTRY struct for later
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.286p
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MR_HeapSel:
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mov dx,WORD PTR dwOffset[2] ;Get the HIWORD of segment offset
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cmp dx,WORD PTR Global.ge_dwBlockSize[2] ;Check HIWORD of size
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jb MR_OK ;Offset should be OK
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je @F ;Equal. Must check LOWORD
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jmp MR_Bad ;Offset is not inside segment
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@@: mov ax,WORD PTR dwOffset[0] ;Get the LOWORD of segment offset
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cmp ax,WORD PTR Global.ge_dwBlockSize[0] ;Check LOWORD of size
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jb MR_OK ;It's inside segment
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jmp MR_Bad ;Not inside segment
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MR_OK:
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;** Do different stuff on 286 and 386/486
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mov ax,__WinFlags ;Get the flags
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test ax,WF_CPU286 ;286?
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jnz MR_Do16Bit ;Yes, do 16 bit stuff
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;** Do this the 386 way (easy)
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.386p
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mov ax,wSelector ;Point with DS
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mov ds,ax ; (keep copy in AX)
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mov esi,dwOffset ;Point into the big segment
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mov ecx,dwcb ;Get the copy length
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lsl edx,eax ;Get the segment limit
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sub edx,esi ;Get distance from offset to limit
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inc edx ;Make this the real length
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cmp ecx,edx ;Are we within the limit?
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jbe SHORT MR_LimitOK ;Yes
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mov ecx,edx ;No, so make this the copy amount
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MR_LimitOK:
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mov edx,ecx ;Get the # of bytes to read for ret
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xor edi,edi ;Clear the high word
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les di,lpBuffer ;Point to the dest. buffer
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mov ax,cx ;Save the low bits of ECX
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shr ecx,2 ;Prepare for DWORD move
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jecxz @F ;No zero-length DWORD moves!
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rep movs DWORD PTR [edi],DWORD PTR [esi]
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db 67h ;Handles 386 bug
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db 90h
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@@: mov cx,ax ;Get a copy
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jecxz @F ;Don't do zero!
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and cx,03 ;Do the remaining 3,2, or 1
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rep movs BYTE PTR [edi], BYTE PTR [esi]
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db 67h ;Handles 386 bug
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db 90h
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@@: mov ax,dx ;Bytes copied returned in DX:AX
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shr edx,16
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jmp MR_End ;Get out
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.286p
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;** Do this the 286 way (hard)
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MR_Do16Bit:
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;** Compute the actual copy length
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mov ax,WORD PTR Global.ge_dwBlockSize[0] ;Get the segment size
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mov dx,WORD PTR Global.ge_dwBlockSize[2]
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sub ax,WORD PTR dwOffset[0] ;Get distance from offset to limit
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sbb dx,WORD PTR dwOffset[2]
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cmp dx,WORD PTR dwcb[2] ;Off end of heap block?
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ja MR_LimOk ;No, just do it
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jb MR_Truncate ;Yes, must truncate our length
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cmp ax,WORD PTR dwcb[0] ;Are we off the end?
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jae MR_LimOk ;No, just do it
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MR_Truncate:
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mov WORD PTR dwcb[0],ax ;Force this to be the new length
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mov WORD PTR dwcb[2],dx
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MR_LimOk:
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;** Save the number of bytes to be copied for the return value
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mov ax,WORD PTR dwcb[0] ;Get the LOWORD
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mov WORD PTR dwcbCopied[0],ax ;Save it
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mov ax,WORD PTR dwcb[2] ;Get the HIWORD
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mov WORD PTR dwcbCopied[2],ax ;Save it
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;** Position the initial copying selectors
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mov al,BYTE PTR dwOffset[2] ;Grab the HIWORD (286 is only 24 bits)
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mov ah,__AHINCR ;Get the selector inc value
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mul ah ;Multiply to get sel offset
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add ax,wSelector ;AX = sel in sel array
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mov ds,ax ;Point to this with DS
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mov si,WORD PTR dwOffset[0] ;Get the current pointers
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les di,lpBuffer
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;** This is the main copying loop
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MR_CopyLoop:
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;** Compute the size of this block copy. This is done by finding the
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;* smaller of the following quantities:
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;* - Distance to end of source segment
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;* - Distance to end of dest. segment
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;** - Distance to end of copy
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xor bx,bx ;Flags start at zero
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xor cx,cx ;Get the highest segment value (64K)
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cmp di,si ;The bigger of the two will win
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je MR_Equal ;They're the same
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ja MR_DIBigger ;DI is bigger
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sub cx,si ;SI bigger, compute dist to end
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or bx,SI_CRITICAL ;Flag set for SI-critical
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jmp SHORT MR_CheckEndCopy ;Go on
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MR_Equal:
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sub cx,di ;Use DI (SI and DI are the same)
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or bx,SI_CRITICAL OR DI_CRITICAL ;Both will come true
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jmp SHORT MR_CheckEndCopy ;Go on
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MR_DIBigger:
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sub cx,di ;SI is bigger
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or bx,DI_CRITICAL ;Flag clear for DI-critical
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MR_CheckEndCopy:
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cmp WORD PTR dwcb[2],0 ;Check for less than 64K left
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ja MR_DoCopy ;Nope. More than 64K left
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jcxz MR_GetSize ;CX = 0 is full 64K segment
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cmp WORD PTR dwcb[0],cx ;Less than in either segment left?
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ja MR_DoCopy ;No. Do it
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MR_GetSize:
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mov cx,WORD PTR dwcb[0] ;Get in CX
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MR_DoCopy:
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;** Do this block of 64K or less.
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mov dx,cx ;Save the number of bytes we did
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jcxz @F ;Do 64K
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shr cx,1 ;Do WORDS
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jmp SHORT MR_10 ;Skip over
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@@: mov cx,8000h ;32K WORDS
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MR_10: jcxz @F ;No zero length WORD moves!
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rep movsw ;Do the copy
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@@: mov cx,dx ;Get any remaining bits
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and cx,1 ;Any more to do?
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jcxz @F ;No, don't do it
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movsb ;Do the odd byte if necessary
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@@: mov cx,dx ;Get back in CX
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;** Bump the loop pointers
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jcxz MR_BigCount ;We did 64K
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sub WORD PTR dwcb[0],cx ;Subtract the bytes done
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sbb WORD PTR dwcb[2],0 ; and don't forget the HIWORD
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jmp SHORT MR_20 ;Continue
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MR_BigCount:
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sub WORD PTR dwcb[2],1 ;Subtract 64K
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MR_20: mov ax,WORD PTR dwcb[0] ;We're done if the count of bytes
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or ax,WORD PTR dwcb[2] ; is zero
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jnz @F ;Not zero, go on
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mov dx,WORD PTR dwcbCopied[2] ;Get the return count
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mov ax,WORD PTR dwcbCopied[0]
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jmp SHORT MR_End ;Get out
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@@: test bx,SI_CRITICAL ;Does SI need incrementing?
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jz MR_TestDI ;No, try DI
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mov ax,ds ;Get the segment value
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add ax,__AHINCR ;Bump to next selector
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mov ds,ax ;Point with DS still
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xor si,si ;Point to start of this segment
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MR_TestDI:
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test bx,DI_CRITICAL ;Does SI need incrementing?
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jz MR_Continue ;No, try DI
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mov ax,es ;Get the segment value
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add ax,__AHINCR ;Bump to next selector
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mov es,ax ;Point with DS still
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xor di,di ;Point to start of this segment
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MR_Continue:
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jmp MR_CopyLoop ;Do it again
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MR_Bad:
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xor ax,ax ;Return DWORD 0
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cwd
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MR_End:
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cEnd
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; MemoryWrite
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; Uses the passed in selector and offset to write memory from a user-
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; specified buffer. This works for >64K segments and, if code, may
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; have been discarded. The selector may be a selector or a handle
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; but MUST be on the global heap (no aliases or selector array
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; members). If worried about low memory conditions, lpBuffer should
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; be in a (temporarily) fixed segment.
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;
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; Prototype:
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; DWORD MemoryWrite(
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; WORD wSel, /* Selector to read from */
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; DWORD dwOffset, /* Offset to read at */
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; LPSTR lpBuffer, /* Buffer to put data into */
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; DWORD dwcb) /* Number of characters to read */
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; Returns number of characters read (ends at segment limit)
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cProc MemoryWrite, <FAR,PUBLIC>, <si,di,ds>
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parmW wSelector
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parmD dwOffset
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parmD lpBuffer
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parmD dwcb
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localW wSelFlag
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localD dwcbCopied
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localV DPMISelBuf,8
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localV Global,<SIZE GLOBALENTRY>
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cBegin
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;** Make sure the segment is present. We only will fault the
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;** segment in if it is a code segment
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cCall HelperHandleToSel, <wSelector> ;Convert to sel from handle
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mov wSelector, ax ;Save it
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mov cx,ax ;Get the selector
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push WORD PTR lpBuffer[2] ;Convert handle to selector
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cCall HelperHandleToSel
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mov WORD PTR lpBuffer[2], ax ;Save converted handle
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mov wSelFlag,0 ;Clear the flag
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lar ax,cx ;Get the access rights
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jnz MW_ShortBad ;Failed
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test ax,8000h ;Is it present?
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jnz MW_Present ;Yes
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test ax,0800h ;This bit set for code segments
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jnz MW_FaultIn ;Code segment, fault it in
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MW_ShortBad:
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jmp MW_Bad ;Return error
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MW_FaultIn:
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mov es,wSelector ;Get the selector in ES.
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mov al,es:[0] ;Must be at least one byte long
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MW_Present:
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;** Check this block's length. We use the global heap functions
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;* to do this because they check in the arena for the length.
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;* This is the only way to get lengths of 286 heap blocks
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;** beyond 64K.
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mov ax,SIZE GLOBALENTRY ;Get the size of the structure
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mov WORD PTR Global.ge_dwSize[0],ax ;Save in the structure
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mov WORD PTR Global.ge_dwSize[2],0 ;Clear the HIWORD
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lea ax,Global ;Point to the structure
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cCall GlobalEntryHandle, <ss,ax,wSelector>
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or ax,ax ;Was this a valid selector?
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jnz MW_HeapSel ;Yes, this is a heap selector
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;** If this wasn't a heap selector, we get the length with an LSL.
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;** When used like this, 64K is the max on a 286
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MW_NonHeap:
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mov bx,wSelector ;Get the selector
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mov ax,__WinFlags ;Get the flags
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test ax,WF_CPU286 ;286?
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jz MW_32BitSize ;No, do 32 bit size stuff
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lsl dx,bx ;Get length in DX
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mov WORD PTR Global.ge_dwBlockSize[0],dx ;Put in GLOBALENTRY struct
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mov WORD PTR Global.ge_dwBlockSize[2],0
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jmp SHORT MW_HeapSel
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MW_32BitSize:
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.386p
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lsl edx,ebx
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mov Global.ge_dwBlockSize,edx ;Put in GLOBALENTRY struct for later
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.286p
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MW_HeapSel:
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mov dx,WORD PTR dwOffset[2] ;Get the HIWORD of segment offset
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cmp dx,WORD PTR Global.ge_dwBlockSize[2] ;Check HIWORD of size
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jb MW_OK ;Offset should be OK
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je @F ;Equal. Must check LOWORD
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jmp MW_Bad ;Offset is not inside segment
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@@: mov ax,WORD PTR dwOffset[0] ;Get the LOWORD of segment offset
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cmp ax,WORD PTR Global.ge_dwBlockSize[0] ;Check LOWORD of size
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jb MW_OK ;It's inside segment
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jmp MW_Bad ;Not inside segment
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MW_OK:
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;** Do different stuff on 286 and 386/486
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mov ax,__WinFlags ;Get the flags
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test ax,WF_CPU286 ;286?
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jnz MW_Do16Bit ;Yes, do 16 bit stuff
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;** Do this the 386 way (easy)
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.386p
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;** Get an alias selector if necessary
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mov ax,wSelector ;Get the source selector
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push ss ;Get ES = SS
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pop es
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lea di,DPMISelBuf ;Point to our descriptor buffer
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cCall MakeAlias ;Make the alias selector
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jnc SHORT @F ;No error
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jmp MW_Bad ;Must be error
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@@: mov wSelFlag,bx ;Set the selector flag
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mov wSelector,ax ;Save the new selector
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;** Do the copying
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mov ax,wSelector ;Point with DS
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mov es,ax ; (keep copy in AX)
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mov edi,dwOffset ;Point into the big segment
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mov ecx,dwcb ;Get the copy length
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lsl edx,eax ;Get the segment limit
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sub edx,edi ;Get distance from offset to limit
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inc edx ;Make this the real length
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cmp ecx,edx ;Are we within the limit?
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jbe SHORT MW_LimitOK ;Yes
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mov ecx,edx ;No, so make this the copy amount
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MW_LimitOK:
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xor esi,esi ;Clear the high word
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lds si,lpBuffer ;Point to the dest. buffer
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mov eax,ecx ;Save ECX
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shr ecx,2 ;Prepare for DWORD move
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jecxz @F ;No zero-length DWORD moves!
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rep movs DWORD PTR [edi],DWORD PTR [esi]
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db 67h ;Handles 386 bug
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db 90h
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@@: mov ecx,eax ;Get a copy
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jecxz @F ;Don't do zero!
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and ecx,03 ;Do the remaining 3,2, or 1
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rep movs BYTE PTR [edi], BYTE PTR [esi]
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db 67h ;Handles 386 bug
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db 90h
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@@: mov edx,eax ;Bytes copied returned in DX:AX
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shr edx,16
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;** Free alias if necessary
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push ax ;Save return value
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push dx
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cmp wSelFlag,0 ;Selector flag set?
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je SHORT @F ;Nope
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mov ax,1 ;DPMI function - Free Selector
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mov bx,wSelector ;Selector to free
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int 31h ;Call DPMI
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@@: pop dx
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pop ax
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jmp MW_End ;Get out
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.286p
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;** Do this the 286 way (hard)
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MW_Do16Bit:
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;** Compute the actual copy length
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mov ax,WORD PTR Global.ge_dwBlockSize[0] ;Get the segment size
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mov dx,WORD PTR Global.ge_dwBlockSize[2]
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sub ax,WORD PTR dwOffset[0] ;Get distance from offset to limit
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sbb dx,WORD PTR dwOffset[2]
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cmp dx,WORD PTR dwcb[2] ;Off end of heap block?
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ja MW_LimOk ;No, just do it
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jb MW_Truncate ;Yes, must truncate our length
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cmp ax,WORD PTR dwcb[0] ;Are we off the end?
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jae MW_LimOk ;No, just do it
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MW_Truncate:
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mov WORD PTR dwcb[0],ax ;Force this to be the new length
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mov WORD PTR dwcb[2],dx
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MW_LimOk:
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;** Save the number of bytes to be copied for the return value
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mov ax,WORD PTR dwcb[0] ;Get the LOWORD
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mov WORD PTR dwcbCopied[0],ax ;Save it
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mov ax,WORD PTR dwcb[2] ;Get the HIWORD
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mov WORD PTR dwcbCopied[2],ax ;Save it
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;** Position the initial copying selectors
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mov al,BYTE PTR dwOffset[2] ;Grab the HIWORD (286 is only 24 bits)
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mov ah,__AHINCR ;Get the selector inc value
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mul ah ;Multiply to get sel offset
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add ax,wSelector ;AX = sel in sel array
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mov es,ax ;Point to this with DS
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mov di,WORD PTR dwOffset[0] ;Get the current pointers
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lds si,lpBuffer
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;** This is the main copying loop
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MW_CopyLoop:
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;** Get an alias selector if necessary
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push si ;Save regs
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push di
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mov ax,es ;Get the source selector
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push ss ;Get ES = SS
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pop es
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lea di,DPMISelBuf ;Point to our descriptor buffer
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cCall MakeAlias ;Make the alias selector
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pop di ;Restore regs
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pop si
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jnc @F ;No error
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jmp MW_Bad ;Must be error
|
|
@@: mov wSelFlag,bx ;Set the selector flag
|
|
mov es,ax ;Save the new selector
|
|
|
|
;** Compute the size of this block copy. This is done by finding the
|
|
;* smaller of the following quantities:
|
|
;* - Distance to end of source segment
|
|
;* - Distance to end of dest. segment
|
|
;** - Distance to end of copy
|
|
xor bx,bx ;Flags start at zero
|
|
xor cx,cx ;Get the highest segment value (64K)
|
|
cmp di,si ;The bigger of the two will win
|
|
je MW_Equal ;They're the same
|
|
ja MW_DIBigger ;DI is bigger
|
|
sub cx,si ;SI bigger, compute dist to end
|
|
or bx,SI_CRITICAL ;Flag set for SI-critical
|
|
jmp SHORT MW_CheckEndCopy ;Go on
|
|
MW_Equal:
|
|
sub cx,di ;Use DI (SI and DI are the same)
|
|
or bx,SI_CRITICAL OR DI_CRITICAL ;Both will come true
|
|
jmp SHORT MW_CheckEndCopy ;Go on
|
|
MW_DIBigger:
|
|
sub cx,di ;SI is bigger
|
|
or bx,DI_CRITICAL ;Flag clear for DI-critical
|
|
MW_CheckEndCopy:
|
|
cmp WORD PTR dwcb[2],0 ;Check for less than 64K left
|
|
ja MW_DoCopy ;Nope. More than 64K left
|
|
jcxz MW_GetSize ;CX = 0 is full 64K segment
|
|
cmp WORD PTR dwcb[0],cx ;Less than in either segment left?
|
|
ja MW_DoCopy ;No. Do it
|
|
MW_GetSize:
|
|
mov cx,WORD PTR dwcb[0] ;Get in CX
|
|
MW_DoCopy:
|
|
|
|
;** Do this block of 64K or less.
|
|
mov dx,cx ;Save the number of bytes we did
|
|
jcxz @F ;Do 64K
|
|
shr cx,1 ;Do WORDS
|
|
jmp SHORT MW_10 ;Skip over
|
|
@@: mov cx,8000h ;32K WORDS
|
|
MW_10: jcxz @F ;No zero-length WORD moves
|
|
rep movsw ;Do the copy
|
|
@@: mov cx,dx ;Get any remaining bits
|
|
and cx,1 ;Any more to do?
|
|
jcxz @F ;No, don't do it
|
|
movsb ;Do the odd byte if necessary
|
|
@@: mov cx,dx ;Get back in CX
|
|
|
|
;** Bump the loop pointers
|
|
jcxz MW_BigCount ;We did 64K
|
|
sub WORD PTR dwcb[0],cx ;Subtract the bytes done
|
|
sbb WORD PTR dwcb[2],0 ; and don't forget the HIWORD
|
|
jmp SHORT MW_20 ;Continue
|
|
MW_BigCount:
|
|
sub WORD PTR dwcb[2],1 ;Subtract 64K
|
|
MW_20: mov ax,WORD PTR dwcb[0] ;We're done if the count of bytes
|
|
or ax,WORD PTR dwcb[2] ; is zero
|
|
jnz @F ;Not zero, go on
|
|
mov dx,WORD PTR dwcbCopied[2] ;Get the return count
|
|
mov ax,WORD PTR dwcbCopied[0]
|
|
jmp SHORT MW_End ;Get out
|
|
@@: test bx,SI_CRITICAL ;Does SI need incrementing?
|
|
jz MW_TestDI ;No, try DI
|
|
mov ax,ds ;Get the segment value
|
|
add ax,__AHINCR ;Bump to next selector
|
|
mov ds,ax ;Point with DS still
|
|
xor si,si ;Point to start of this segment
|
|
MW_TestDI:
|
|
test bx,DI_CRITICAL ;Does SI need incrementing?
|
|
jz MW_Continue ;No, try DI
|
|
mov ax,es ;Get the segment value
|
|
add ax,__AHINCR ;Bump to next selector
|
|
mov es,ax ;Point with DS still
|
|
xor di,di ;Point to start of this segment
|
|
MW_Continue:
|
|
|
|
;** Free alias if necessary
|
|
cmp wSelFlag,0 ;Selector flag set?
|
|
je @F ;Nope
|
|
mov ax,1 ;DPMI function - Free Selector
|
|
mov bx,wSelector ;Selector to free
|
|
int 31h ;Call DPMI
|
|
@@: jmp MW_CopyLoop ;Do it again
|
|
|
|
MW_Bad:
|
|
xor ax,ax ;Return DWORD 0
|
|
cwd
|
|
|
|
MW_End:
|
|
|
|
cEnd
|
|
|
|
|
|
;** Helper functions
|
|
|
|
; MakeAlias
|
|
; Makes an alias selector for the selector in AX. The new selector
|
|
; is returned in AX. Carry is set on exit if error.
|
|
; Returns nonzero in BX if an alias was made, zero if not
|
|
; ES:DI points to an 8-byte descriptor buffer
|
|
|
|
cProc MakeAlias, <NEAR, PUBLIC>, <si,di>
|
|
cBegin
|
|
|
|
;** If this is not a read/write selector, we must create an alias.
|
|
;* In order to be able to free up the selector, we set a flag
|
|
;** so we know to free it.
|
|
xor si,si ;No alias made, just in case
|
|
lar cx,ax ;Get its access rights
|
|
jnz MA_Bad ;Failed
|
|
test cx,800h ;Is this a code segment?
|
|
jnz MA_MakeAlias ;Yes. Always make an alias
|
|
test cx,200h ;Is it read/write?
|
|
jnz MA_End ;Yes, no need for alias
|
|
MA_MakeAlias:
|
|
mov bx,ax ;Get the selector
|
|
mov ax,0bh ;DPMI function - Get Descriptor
|
|
;ES:DI already point to buffer
|
|
int 31h ;Call DPMI
|
|
jc MA_Bad ;Error
|
|
xor ax,ax ;DPMI Function - Alloc selector
|
|
mov cx,1 ;Alloc 1 selector
|
|
int 31h ;Call DPMI
|
|
jc MA_Bad ;Error
|
|
mov si,1 ;Set flag to say alias made
|
|
and BYTE PTR DPMISelBuf[5],0f0h ;Mask out unwanted bits
|
|
or BYTE PTR DPMISelBuf[5],2 ;Make it a R/W Data segment
|
|
mov bx,ax ;Selector in BX
|
|
mov ax,0ch ;DPMI function - Set Descriptor
|
|
int 31h ;Call DPMI
|
|
jc MA_Bad ;Error
|
|
mov ax,bx ;Get the new selector in AX
|
|
jmp SHORT MA_End ;Get out
|
|
|
|
MA_Bad:
|
|
stc ;Error
|
|
|
|
MA_End:
|
|
mov bx,si ;Get flag in BX
|
|
cEnd
|
|
|
|
|
|
sEnd
|
|
|
|
END
|
|
|